Add game-of-life exercise (#450)

config.json

@@ -917,6 +917,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 1
+      },
+      {
+        "slug": "game-of-life",
+        "name": "Conway's Game of Life",
+        "uuid": "a5fb2249-46ec-4e6e-bc4f-947f0e0a7193",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
       }
     ],
     "foregone": [

exercises/practice/game-of-life/.docs/instructions.md

@@ -0,0 +1,11 @@
+# Instructions
+
+After each generation, the cells interact with their eight neighbors, which are cells adjacent horizontally, vertically, or diagonally.
+
+The following rules are applied to each cell:
+
+- Any live cell with two or three live neighbors lives on.
+- Any dead cell with exactly three live neighbors becomes a live cell.
+- All other cells die or stay dead.
+
+Given a matrix of 1s and 0s (corresponding to live and dead cells), apply the rules to each cell, and return the next generation.

exercises/practice/game-of-life/.docs/introduction.md

@@ -0,0 +1,9 @@
+# Introduction
+
+[Conway's Game of Life][game-of-life] is a fascinating cellular automaton created by the British mathematician John Horton Conway in 1970.
+
+The game consists of a two-dimensional grid of cells that can either be "alive" or "dead."
+
+After each generation, the cells interact with their eight neighbors via a set of rules, which define the new generation.
+
+[game-of-life]: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life

exercises/practice/game-of-life/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "game_of_life.pl"
+    ],
+    "test": [
+      "game_of_life_tests.plt"
+    ],
+    "example": [
+      ".meta/game_of_life.example.pl"
+    ]
+  },
+  "blurb": "Implement Conway's Game of Life.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life"
+}

exercises/practice/game-of-life/.meta/game_of_life.example.pl

@@ -0,0 +1,27 @@
+:- use_module(library(clpfd)).
+
+cell(Rows, X, Y, Cell) :- nth1(Y, Rows, Row), nth1(X, Row, Cell).
+
+live_neighbor(Rows, X, Y) :-
+    between(-1, 1, Dx),
+    between(-1, 1, Dy),
+    NeighborX #= X + Dx,
+    NeighborY #= Y + Dy,
+    (NeighborX #\= X #\/ NeighborY #\= Y),
+    cell(Rows, NeighborX, NeighborY, 1).
+
+next_cell(Rows, Y, Cell, X, NextCell) :-
+    findall(1, live_neighbor(Rows, X, Y), LiveNeighbors),
+    length(LiveNeighbors, Count),
+    (Count #= 3; Count #= 2, Cell = 1) -> NextCell = 1; NextCell = 0.
+
+next_row(Rows, Y, Row, NextRow) :-
+    length(Row, Length),
+    numlist(1, Length, Xs),
+    maplist(next_cell(Rows, Y), Row, Xs, NextRow).
+
+tick([], []) :- !.
+tick(Current, Next) :-
+    length(Current, Height),
+    numlist(1, Height, Ys),
+    maplist(next_row(Current), Ys, Current, Next).

exercises/practice/game-of-life/.meta/tests.toml

@@ -0,0 +1,34 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[ae86ea7d-bd07-4357-90b3-ac7d256bd5c5]
+description = "empty matrix"
+
+[4ea5ccb7-7b73-4281-954a-bed1b0f139a5]
+description = "live cells with zero live neighbors die"
+
+[df245adc-14ff-4f9c-b2ae-f465ef5321b2]
+description = "live cells with only one live neighbor die"
+
+[2a713b56-283c-48c8-adae-1d21306c80ae]
+description = "live cells with two live neighbors stay alive"
+
+[86d5c5a5-ab7b-41a1-8907-c9b3fc5e9dae]
+description = "live cells with three live neighbors stay alive"
+
+[015f60ac-39d8-4c6c-8328-57f334fc9f89]
+description = "dead cells with three live neighbors become alive"
+
+[2ee69c00-9d41-4b8b-89da-5832e735ccf1]
+description = "live cells with four or more neighbors die"
+
+[a79b42be-ed6c-4e27-9206-43da08697ef6]
+description = "bigger matrix"

exercises/practice/game-of-life/game_of_life.pl

@@ -0,0 +1 @@
+tick(Current, Next).

exercises/practice/game-of-life/game_of_life_tests.plt

@@ -0,0 +1,115 @@
+pending :-
+    current_prolog_flag(argv, ['--all'|_]).
+pending :-
+    write('\nA TEST IS PENDING!\n'),
+    fail.
+
+:- begin_tests(game_of_life).
+
+    test(empty_matrix, condition(true)) :-
+        Current = [],
+        tick(Current, Next),
+        Next == [].
+
+    test(live_cells_with_zero_live_neighbors_die, condition(pending)) :-
+        Current = [
+            [0, 0, 0],
+            [0, 1, 0],
+            [0, 0, 0]
+        ],
+        tick(Current, Next),
+        Next == [
+            [0, 0, 0],
+            [0, 0, 0],
+            [0, 0, 0]
+        ].
+
+    test(live_cells_with_only_one_live_neighbor_die, condition(pending)) :-
+        Current = [
+            [0, 0, 0],
+            [0, 1, 0],
+            [0, 1, 0]
+        ],
+        tick(Current, Next),
+        Next == [
+            [0, 0, 0],
+            [0, 0, 0],
+            [0, 0, 0]
+        ].
+
+    test(live_cells_with_two_live_neighbors_stay_alive, condition(pending)) :-
+        Current = [
+            [1, 0, 1],
+            [1, 0, 1],
+            [1, 0, 1]
+        ],
+        tick(Current, Next),
+        Next == [
+            [0, 0, 0],
+            [1, 0, 1],
+            [0, 0, 0]
+        ].
+
+    test(live_cells_with_three_live_neighbors_stay_alive, condition(pending)) :-
+        Current = [
+            [0, 1, 0],
+            [1, 0, 0],
+            [1, 1, 0]
+        ],
+        tick(Current, Next),
+        Next == [
+            [0, 0, 0],
+            [1, 0, 0],
+            [1, 1, 0]
+        ].
+
+    test(dead_cells_with_three_live_neighbors_become_alive, condition(pending)) :-
+        Current = [
+            [1, 1, 0],
+            [0, 0, 0],
+            [1, 0, 0]
+        ],
+        tick(Current, Next),
+        Next == [
+            [0, 0, 0],
+            [1, 1, 0],
+            [0, 0, 0]
+        ].
+
+    test(live_cells_with_four_or_more_neighbors_die, condition(pending)) :-
+        Current = [
+            [1, 1, 1],
+            [1, 1, 1],
+            [1, 1, 1]
+        ],
+        tick(Current, Next),
+        Next == [
+            [1, 0, 1],
+            [0, 0, 0],
+            [1, 0, 1]
+        ].
+
+    test(bigger_matrix, condition(pending)) :-
+        Current = [
+            [1, 1, 0, 1, 1, 0, 0, 0],
+            [1, 0, 1, 1, 0, 0, 0, 0],
+            [1, 1, 1, 0, 0, 1, 1, 1],
+            [0, 0, 0, 0, 0, 1, 1, 0],
+            [1, 0, 0, 0, 1, 1, 0, 0],
+            [1, 1, 0, 0, 0, 1, 1, 1],
+            [0, 0, 1, 0, 1, 0, 0, 1],
+            [1, 0, 0, 0, 0, 0, 1, 1]
+        ],
+        tick(Current, Next),
+        Next == [
+            [1, 1, 0, 1, 1, 0, 0, 0],
+            [0, 0, 0, 0, 0, 1, 1, 0],
+            [1, 0, 1, 1, 1, 1, 0, 1],
+            [1, 0, 0, 0, 0, 0, 0, 1],
+            [1, 1, 0, 0, 1, 0, 0, 1],
+            [1, 1, 0, 1, 0, 0, 0, 1],
+            [1, 0, 0, 0, 0, 0, 0, 0],
+            [0, 0, 0, 0, 0, 0, 1, 1]
+        ].
+
+:- end_tests(game_of_life).